Because there is no medical test that can be given to diagnose autism, professionals depend on observing the behaviors of the person in question as well as the medical and developmental history. There are behavioral checklists available that are used to determine if the person has the specific number of characteristics as defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), which is the standard reference for the definition of autism. A good diagnostic checklist is available through the Autism Research Institute (www.autismresearchinstitute.com).
This medical diagnostic handbook, currently in its fourth edition, is internationally used and recognized. When the DSM was revised in 1994, some changes were made. Previously, the category of pervasive developmental disorders (PDD), which includes autism, was coded or classified with other long-term stable disorders that have a poor prognosis. Now PDD has been classified with more transient, temporary, and episodic clinical disorders. This is a positive move that reflects what current research is now showing: that there is a possibility of improvement with intervention, and that symptoms can vary in intensity.
The diagnostic criteria for autism have changed slightly as well. In order for a person to be diagnosed with autism, he or she still needs to show deficits in the broad areas of social interaction, communication, and stereotyped patterns. However, the number of symptoms that fall under these categories has been reduced from sixteen to twelve, making this diagnostic category more homogeneous. A third change made was the addition of three new autism-related disorders: Rett's disorder, childhood disintegrative disorder, and Asperger's syndrome.
All individuals who fall under the PDD category in the DSM-IV have some communication and social deficits, but the levels of severity are different. Here are the differences between specific diagnoses that are used:
- Autistic disorder (or classic autism): A child with this disorder shows impairments in imaginative play, social interaction, and communication, with an onset before the age of three. The child exhibits stereotyped behaviors, activities, and interests.
- Childhood disintegrative disorder: The child develops normally and has age-appropriate verbal and nonverbal communication skills, social relationships, play, and adaptive behaviors for at least the first two years and then shows a significant loss of previously acquired skills.
- Rett's disorder: So far, only girls have had this progressive disorder. There is a period of normal development through the first five months and then a loss of previously acquired skills. The girl loses the purposeful use of her hands, which is replaced with hand wringing. There is severe psychomotor delay and a poorly coordinated gait. (It is now possible, thanks to the recent development of a new genetic blood test, to test for this disorder.)
- Asperger's syndrome: A child with Asperger's tests in the range of average to above average intelligence and has no clinically significant general delay in language. However, the child will show impairments in social interactions, including difficulty in using social cues such as body language, and has a restricted range of interests and activities.
- Pervasive developmental disorder not otherwise specified (atypical autism): A diagnosis of PDD-NOS may be made when a child does not meet the criteria for a specific diagnosis, but there is a severe and pervasive impairment in specified behaviors.
You may wish to consult the diagnostic criteria from DSM-IVatwww.psychologynet.org/autism.html or at www.pediatricneurology.com.